jcmusic Posted January 20, 2007 Share Posted January 20, 2007 I have a rooftop antenna with two seperate runs, to two different tuners. The other day I noticed when I moved one of the tuners into another room the signal strength doubled. What would cause this? I am not using a splitter, would this cause the line not in use to pickup unwanted signals? Also must the antenna be grounded? What is the noise I am hearing that sounds like static, when I have a strong signal? Jay Quote Link to comment Share on other sites More sharing options...
JJkizak Posted January 20, 2007 Share Posted January 20, 2007 Your going to have to go up on the roof and see how those lines are hooked up, maybe one of them isn't and maybe there is a splitter up there with a matching transformer. Maybe bad connections too. JJK Quote Link to comment Share on other sites More sharing options...
pauln Posted January 20, 2007 Share Posted January 20, 2007 I have a rooftop antenna with two seperate runs, to two different tuners. The other day I noticed when I moved one of the tuners into another room the signal strength doubled. What would cause this? I am not using a splitter, would this cause the line not in use to pickup unwanted signals? Also must the antenna be grounded? What is the noise I am hearing that sounds like static, when I have a strong signal? Jay What kind of antenne? Is is a "T" shape for FM, a vertical element, or an array? Sounds like the runs are participating in the receiving function of the antenne. Without a switch, both runs may be participating even when not "in use". All lines always pickup signals. The anntene should be grounded. Static is caused by natural things, radio noise from space, electrical storms (lightening hits the Earth about 1000 times per second and depending on the receiving wavelength most of it may be heard), local electrical motors, computers, some lighting fixtures... Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 20, 2007 Share Posted January 20, 2007 Not to hijack, but a question on the same subject. After hearing the question, it will be obvious to you that I know nothing of FM antennas. I am not a FM guy because: 1) There no stations in my "urban" area with anything to intrest me other than news and sports (one can only listen to freebird so many times) 2) I live in the sticks, and a mountainous area 3) Have tried many indoor units without acceptable results - also connected to big roof unit, same results Why does my stock Ford radio in the driveway pick up all stations with reasonable quility, where nothing else will?????? tc Quote Link to comment Share on other sites More sharing options...
Diamond45 Posted January 20, 2007 Share Posted January 20, 2007 Why does my stock Ford radio in the driveway pick up all stations with reasonable quility, where nothing else will?????? Car radios are made to receive weak signals better. This is true for FM, not necessarily true for AM. Also, car radios have a special FM system where if a signal is weak, it will "blend" stereo and mono audio, going to mono if all else fails. (Stereo FM is actually an FM mono signal with an AM difference signal which the radio reconstructs the left and right channels.) If you're looking for a good portable AM/FM radio, look for the GE SuperRadio III. The CCradio from C. Crane is also a good portable AM/FM radio. Be prepared to pay top dollar for these radios. What kind of receiver are you using to try to receive out of town stations? All indoor FM antennas I've tried are bad. I don't have the luxury to try an outdoor antenna. Quote Link to comment Share on other sites More sharing options...
jcmusic Posted January 20, 2007 Author Share Posted January 20, 2007 Pauln the antenna is called an FM 6, it's on a 5 foot mast on my roof pointed at station i want to listen to. As for the grounding, do I just need one of those kits? Are is there something else I can do? Jay Quote Link to comment Share on other sites More sharing options...
Doc Robin Posted January 20, 2007 Share Posted January 20, 2007 Radio signals are sent out in vertical polarization hince the vertical antenna on the truck. The big TV type Yagi horizontal antenna,s dont pick up the vertical signals as well. Also the TV type has multi elements to it's design; these make it directional thus the need to turn the antenna toward the station you are wanting to pick up. The truck antenna is a vetical omni directional antenna. It receives signal's in a 360 degree pattern. Later Bill Quote Link to comment Share on other sites More sharing options...
djk Posted January 21, 2007 Share Posted January 21, 2007 "I have a rooftop antenna with two seperate runs, to two different tuners. The other day I noticed when I moved one of the tuners into another room the signal strength doubled. What would cause this? I am not using a splitter, would this cause the line not in use to pickup unwanted signals? Also must the antenna be grounded? What is the noise I am hearing that sounds like static, when I have a strong signal?" You must use a mast head amplifier and a splitter. The amplifier overcomes the loss of the splitter and the long line to the set. Without this the signal at the set can be lower than if you used a back of the set antenna. The amplifier is phantom powered, and the splitter must be able to pass the phantom voltage to the amplifier. "(Stereo FM is actually an FM mono signal with an AM difference signal which the radio reconstructs the left and right channels.)" The difference signal is also FM. There is no standard for the amount of power in the difference signal. The manufacturer of the receiver commonly designs for 5%, broadcasters put between 3% and 7% of total power into the L-R signal. That's right, up to 97% of the power is in mono. A good antenna/masthead amplifier/tuner can receive signals from 100 miles away (line of sight, depends on the height of the send and receive antennas). But in mono. A Tandberg has a super sounding FM for local stations, but is poor for distant stations. A Carver with the ACCD circuit will not sound as good on local stations, but will allow noise-free stereo from 100 miles out (the ACCD is a very fancy mono-blend that is dependant of the signal strength and the program material). The antenna must be grounded for safety. Quote Link to comment Share on other sites More sharing options...
jcmusic Posted January 21, 2007 Author Share Posted January 21, 2007 djk, In this case I am only interested in getting two stations, 90.7 and 91.5 both are within 7 miles. Do you think I still need the amp? What about the noise when i have a strong signal? What is that? and what causes it? Jay Quote Link to comment Share on other sites More sharing options...
djk Posted January 21, 2007 Share Posted January 21, 2007 "Do you think I still need the amp? " "The amplifier overcomes the loss of the splitter and the long line to the set. Without this the signal at the set can be lower than if you used a back of the set antenna." "In this case I am only interested in getting two stations, 90.7 and 91.5 both are within 7 miles." Are the station antennas in the same place? Without a rotator the signal may be worse with an antenna that big (than with a simple dipole). Either fix the situation up, or get rid of it and use two back of set antennas. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted January 21, 2007 Share Posted January 21, 2007 I found buying terk radio antennas that the best signal is the passive am/fm version. the fm only version really sucks. But I also brough the powered or amplified version which sucked as all it did was imcrease the distortion and hiss. Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 21, 2007 Share Posted January 21, 2007 I'll chime in and give my two cents. I believe FM, like TV, is circularly polarized. So neither horizontal or vertical antenna are the best. You can Google around for home built circularly polarized antennae but I wonder if that is worthwhile. In theory they can help with multipath. If you're a few miles away, signal strength is not a problem. So a head amp is not necessary at all. BTW, in downtown Chicago I have to short out the antenna to the receiver. You may have a multipath problem arising from buildings near the path from transmitter to receiver. I would check the lines and what is going on up at the antenna. If you have the wire there, fine. If I was doing this I'd run down one lead and then split it off. In any case, the unused line must be terminated for best results. Maybe RS sells a screw on 75 ohm termination. They are around. This is because the signal will travel down the line to the end (un terminated) and then reflect back to whatever you have at the antenna, and then back down the other line. This can form a type of multipath within your system. I'd wonder about the quality of the connections up at the antenna unless you did it yourself. I've seen some cable hook ups (cable TV) installed by "professionals" which are just terrible. If you go up on the roof, pay attention to fall protection and your footing. You should also read up on lightening protection for your system. Gil Quote Link to comment Share on other sites More sharing options...
jcmusic Posted January 21, 2007 Author Share Posted January 21, 2007 I did everything myself so that is not an issue, I just don't have much expirence with antenna's, multipath, overload, etc, etc. All I want to do is be able to use either of my two tuners, to listen to one of two stations that are both within 10 miles of me. Jay Quote Link to comment Share on other sites More sharing options...
Poormana Posted January 21, 2007 Share Posted January 21, 2007 I have had the best luck using my entire house as an antenna. Just attach the FM antenna to the ground on an electrical outlet (the center screw holding the faceplate on) and viola! excellent reception. Option B is to use your Cable if you have cable, but that didn't work as good for me. My denon receiver came with a FM antenna that was just a wire with a coax connection on one end (receiver) and a small loop on the other. The loop is so small the screw barely fit through the hole. I can only assume this is what this antenna is for. The best reception I was able to get was either me holding the end of the wire (not very practical for me) or attaching it to an outlet. So far my house hasn't burned down. Andy Denon AVR 2106 Lots of Klipsch speakers. (profile/Signature in the works...) Quote Link to comment Share on other sites More sharing options...
mas Posted January 21, 2007 Share Posted January 21, 2007 Attached you will find information on antenna grounding. The first is NEC approved (with common bonding) and the second variation is not (without common bonding), which also presents an increased likelihood of 'ground loops'. The other small variation is in regards to the siting of the the hardware. While ideally common bonding is desirable for many reasons, attempting to manipulate and install any conductive materials (ladders, antennas, etc.) near power lines and masts is extremely hazardous and should be considered before undue risk is assumed. In addition to grounding and antennas installation is some additional information regrading preamplifier's, amplifiers and distribution amps as well as troubleshooting techniques for some very common reception problems. I will admit to being 'just a bit' confused by the description of 'two runs' originating from the antenna unless they are run from a preamplifier and a splitter (which may be integrated). (Normally such a scenario would only be present from a dual LNA/LNB preamplifier used in a satellite receiver, or after a distribution amplifier in a 'normal' off-air television/FM antenna.). Additionally, termination, cable types, connector types, baluns, etc., etc., etc. are pertinent. And I agree with Gil and djk, why do you have an amplifier for a station 6-7 miles away? More is not better! Nor is overdriving an input stage or amplifying the noise floor. And 75 ohm female terminator caps are readily available - essentially a female F-fitting with an embedded 75 ohm resistor in a stub form factor. You can attach them with a barrel. If you are able to draw an accurate diagram of the exact distribution with all inline devices, active or passive, I would be glad to try and help. But as far as grounding, I hope this helps... TV ANTENNA GROUNDING PROCEDURES.s.pdf Quote Link to comment Share on other sites More sharing options...
djk Posted January 22, 2007 Share Posted January 22, 2007 "If you're a few miles away, signal strength is not a problem. So a head amp is not necessary at all. " At the risk of repeating myself (for the third time): "The amplifier overcomes the loss of the splitter and the long line to the set. Without this the signal at the set can be lower than if you used a back of the set antenna." and : "Either fix the situation up, or get rid of it and use two back of set antennas." If you're not going to do it right, unhook it all and just use a dipole (it will work better at your distance). Quote Link to comment Share on other sites More sharing options...
Doc Robin Posted January 22, 2007 Share Posted January 22, 2007 You should not have a problem with the stations that close; unless you have a metal roof and siding; this would block the siganl from getting to the receiver. I have not had any problems with the local stations most of my antenna experience has been trying to get signals from hundreds to thousands of miles away. Can you post of pictures of the antenna install and the rest of the set up; this will give us a better understanding so we can trouble shoot it better. Later Bill Quote Link to comment Share on other sites More sharing options...
jcmusic Posted January 22, 2007 Author Share Posted January 22, 2007 Ok guys thanks for all the advice, I will try and post some pic's later today. Jay Quote Link to comment Share on other sites More sharing options...
jcmusic Posted January 22, 2007 Author Share Posted January 22, 2007 Here is the first one. Jay Quote Link to comment Share on other sites More sharing options...
jcmusic Posted January 22, 2007 Author Share Posted January 22, 2007 This is where the single line enters the attic from the antenna. Jay Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.